Yes, it is old news. No, they are not DDs.
This is the ATFE's solution to things like the Mossberg PGO shotguns. Because they don't have a shoulder stock they do not fit the definition of a shotgun. Because they are essentially large pistols, they cannot be sold to anyone under 21. ATFE's guidance in this case is to consider them "Other" on the 4473, and not to sell them to those under 21.
That is all.